4.1 block

[usetaboost]

Piss on it, here we go. Here's my take on block strength, which basically is the lower end which everyone is concerned with on all buick v6 engines. I'd choose a girdle, here's why. Metal fatigues. I don't care how tough it is. cranks, rods, bolts, and caps all have stress and it's repeated. 20 yr old parts that have been cycled millions of times. Throw in the stress of hard use (racing) and its gonna weaken rapidly. Grab a piece of metal and constantly bend it. Of course it isn't gonna break the first time you bend it. But do it constantly with more and more stress guess what's gonna happen? Yeah detonation will wipe out the bottom end but stresses are at work also. There is little support for the mains in a production block. Cast iron has very little give, the yield strength and the ultimate tensile strength can't be too far from eachother in this case. In my opinion this is why I will agree with drilling out the top few threads on the deck surface. THe threads won't be pulling on the top of the deck and promoting a crack. Doesn't mean it won't happen but I bet it helps. Back to tacos

 

[usetaboost]

Just like in porn, you gotta spread the load.

 

[turbonut85]

ahhhhh....you, man of many many deep thoughts.....me, merely young grasshoppa....wish to spend many a drunken hour discussing your theories and such.....

 

[usetaboost]

I hope you're ready to talk-I've seen A LOT of porn

 

[jdpolzin]

Piss on it, here we go. Here's my take on block strength, which basically is the lower end which everyone is concerned with on all buick v6 engines. I'd choose a girdle, here's why. Metal fatigues. I don't care how tough it is. cranks, rods, bolts, and caps all have stress and it's repeated. 20 yr old parts that have been cycled millions of times. Throw in the stress of hard use (racing) and its gonna weaken rapidly. Grab a piece of metal and constantly bend it. Of course it isn't gonna break the first time you bend it. But do it constantly with more and more stress guess what's gonna happen? Yeah detonation will wipe out the bottom end but stresses are at work also. There is little support for the mains in a production block. Cast iron has very little give, the yield strength and the ultimate tensile strength can't be too far from eachother in this case. In my opinion this is why I will agree with drilling out the top few threads on the deck surface. THe threads won't be pulling on the top of the deck and promoting a crack. Doesn't mean it won't happen but I bet it helps. Back to tacos

So after reading this a few times, I've decided that you just made a whole lot of ramble to sound really smart to someone out there! J/K man! Get back to bending your fork while eating those tacos!!!!:tongue:

 

[usetaboost]

So after reading this a few times, I've decided that you just made a whole lot of ramble to sound really smart to someone out there! J/K man! Get back to bending your fork while eating those tacos!!!!:tongue:

THey're some big fluckin tacos! You and I are the only ones that know I'm an undercover retard. My government title is "rainman" SHHHHH! Don't tell anyone! I'm off to Kmart to buy underwear before reruns of Wapner start.

 

[usetaboost]

 

[jdpolzin]

View attachment 152881

Oh Man!!!!!! I think I just woke up Ashley and Noah by laughing so hard!!!!!!!!!!!!

 

[Nick Micale]

Thanks for your "2 pennies" Jeremy!

With the 291 block that is now being built, I will recess the deck threaded holes and clean up the casting in the valley area.

This is intended for a high 9 sec. build with an all forged bottom end with caps, but no girdle.

With the bigger 4.1 bore and killer TA heads and a somewhat lightened Regal [3228#'s], it can easily run high 9's with 18-20 psi boost, so it should stay together fine.

As was said in another post, metal fatigues and that will ultimately cause failure. Over the years, we have found that crank flex is probably the most damaging factor.

A forged or billet crank is almost twice as heavy and stronger than a cast crank, and it flexes much less. With the introduction of the in-expensive forged cranks and rods, we have experienced much less wear and failure of the rotating assembly and block.

The flex and harmonics of a cast crank also is very detrimental to the valve train as this unwanted motion is also transmitted to the valve train. A split front cam journal could be a result of this action. We ALWAYS use a real harmonic balancer on an engine operating above 6000 RPM.

Even the early 4.1 we have built with cast cranks have done well and been reliable at the low 10 sec. area, so with improvements in parts, materials, methods and tuning, they should be dependable also well into the 9's.

 

[charlief1]

Thanks for your "2 pennies" Jeremy!

With the 291 block that is now being built, I will recess the deck threaded holes and clean up the casting in the valley area.

This is intended for a high 9 sec. build with an all forged bottom end with caps, but no girdle.

With the bigger 4.1 bore and killer TA heads and a somewhat lightened Regal [3228#'s], it can easily run high 9's with 18-20 psi boost, so it should stay together fine.

As was said in another post, metal fatigues and that will ultimately cause failure. Over the years, we have found that crank flex is probably the most damaging factor.

A forged or billet crank is almost twice as heavy and stronger than a cast crank, and it flexes much less. With the introduction of the in-expensive forged cranks and rods, we have experienced much less wear and failure of the rotating assembly and block.

The flex and harmonics of a cast crank also is very detrimental to the valve train as this unwanted motion is also transmitted to the valve train. A split front cam journal could be a result of this action. We ALWAYS use a real harmonic balancer on an engine operating above 6000 RPM.

Even the early 4.1 we have built with cast cranks have done well and been reliable at the low 10 sec. area, so with improvements in parts, materials, methods and tuning, they should be dependable also well into the 9's.

Have you ever cleaned all the surface off a cast crank and cryoed it Nick?

 

[Nick Micale]

Have you ever cleaned all the surface off a cast crank and cryoed it Nick?

Charlie, to me, it is not worth the $$$ to cryo a cast crank.

However, with the forged, stroker crank going into this 4.1 build, I did have it croyed.

 

[jdpolzin]

Thanks for your "2 pennies" Jeremy!

With the 291 block that is now being built, I will recess the deck threaded holes and clean up the casting in the valley area.

This is intended for a high 9 sec. build with an all forged bottom end with caps, but no girdle.

With the bigger 4.1 bore and killer TA heads and a somewhat lightened Regal [3228#'s], it can easily run high 9's with 18-20 psi boost, so it should stay together fine.

As was said in another post, metal fatigues and that will ultimately cause failure. Over the years, we have found that crank flex is probably the most damaging factor.

A forged or billet crank is almost twice as heavy and stronger than a cast crank, and it flexes much less. With the introduction of the in-expensive forged cranks and rods, we have experienced much less wear and failure of the rotating assembly and block.

The flex and harmonics of a cast crank also is very detrimental to the valve train as this unwanted motion is also transmitted to the valve train. A split front cam journal could be a result of this action. We ALWAYS use a real harmonic balancer on an engine operating above 6000 RPM.

Even the early 4.1 we have built with cast cranks have done well and been reliable at the low 10 sec. area, so with improvements in parts, materials, methods and tuning, they should be dependable also well into the 9's.

No problem Nick! Thanks for all of your help through out the years.

 

[charlief1]

Thanks for the info Nick. I've been thinking about doing it for mine since a forged one is more than I can afford right now.